Field of the Invention
The present invention relates to a method for separating accepts and rejects from a slurry of paper stock and to a high consistency pressure screen for carrying out the method.
Description of the Prior Art
In his U.S. Pat. No. 3,363,759 I. J. Clarke-Pounder discloses a screening device which utilizes a screen or basket having a smooth interior surface spaced from a rotor which has dense and/or projections on its outer surface for producing localized changes in volume in the screening zone. In his U.S. Pat. No. 3,437,204 Clarke-Pounder discloses a similar device in which the rejects are reduced by introducing dilution liquid into the material as it flows through the screening zone and across the screen.
Joseph A. Bolton III and Peter E. LeBlanc, in their U.S. Pat. No. 3,726,401 also disclose the use of a rotor having spaced projections in the form of bumps for creating a pulsation during screening, namely alternate positive screening pulses and negative screen-cleaning pulses.
Ahlstrom Machinery Inc. of Glens Falls, N.Y., produces "profile" screens for use in pressure screen devices.